Femoral cutting block

ABSTRACT

A method of resecting a distal femur is disclosed. The method includes attaching a first block to the distal femur, the first block having a first surface providing a guiding surface for making an anterior chamfer cut on the femur, and a second surface providing a guiding surface for making a posterior chamfer cut on the femur, and making anterior and posterior chamfer cuts on the distal femur. The method further includes attaching a second block to the first block, the second block having a first surface providing a guiding surface for making an anterior cut on the femur, and a second surface providing a guiding surface for making a posterior cut on the femur, and making anterior and posterior cuts on the distal femur.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/642,355, filed on Dec. 20, 2006, the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present application relates generally to the implant of prostheticjoints and pertains, more specifically, to the preparation of the distalfemur for the implantation of a femoral knee prosthesis, utilizing afemoral cutting block to assist in establishing the surfaces necessaryfor locating and securing the prosthesis in place on the femur.

The implant of a prosthetic knee joint requires that the distal femur beprepared to receive the femoral component of the knee prosthesis bycutting the bone of the femur to establish accurately located surfaces.Upon implantation, the femoral component will rest on these surfaces. Asused herein, when referring to bones or other parts of the body, theterm “proximal” means closer to the heart and the term “distal” meansmore distant from the heart. The term “inferior” means toward the feetand the term “superior” means towards the head. The term “anterior”means towards the front part of the body or the face and the term“posterior” means towards the back of the body. The term “medial” meanstoward the midline of the body and the term “lateral” means away fromthe midline of the body.

Various cutting blocks are available to the surgeon for assisting inguiding a saw blade to make the femoral cuts which establish the desiredsurfaces. These guides usually have guide surfaces for making fourresections and are located and secured on the distal femur, upon analready resected transverse surface on the distal femur. Typically,surfaces are provided for guiding the saw blade during the execution ofan axially directed anterior femoral cut, an axially directed posteriorfemoral cut, an anterior chamfer and a posterior chamfer, allspecifically related to the size of the femoral knee prosthesis to beimplanted and to the position and orientation of the femoral kneeprosthesis on the distal femur. A four-in-one cutting block is a singlecutting block for making the four cuts. A four-in-two cutting blockcomprises two separate blocks for making the four cuts. However, suchconventional cutting blocks may exhibit various disadvantages. Forexample, the two blocks of a conventional four-in-two cutting block areused separately and do not interlock to each other. That is, the firstblock is used making a first set of cuts comprising the anterior andposterior chamfer cuts and the second block is used for making a secondset of cuts comprising the anterior and posterior cuts. The first set ofcuts is loosely correlated to the second set of cuts which may decreasethe accuracy of the cuts. In addition, these cutting blocks are made ofmetal which may increase the cost of manufacture. Moreover, because ofthe high cost of such blocks, they are typically reused for additionalsurgical procedures. However, this may require sterilization of theblocks which may be costly and inconvenient.

SUMMARY OF THE INVENTION

The present application discloses a cutting block that may help overcomesome of the above-mentioned disadvantages. The cutting block of thepresent application is a four-in-two (4-in-2) cutting block assemblywhich may improve the accuracy in the preparation of the distal femurfor the implantation of a knee prosthesis. The cutting block assemblycomprises a first block for making the anterior and posterior chamfercuts and a second block for making the anterior and posterior cuts. Thefirst and second blocks interlock which helps correlate the four cutsand improve the accuracy of the cuts. The second block includes extendedcutting surfaces which may further help improve the accuracy of theanterior and posterior cuts. In addition, the second block provides avisual indication of the accuracy of the anterior and posterior chamfercuts before the anterior and posterior cuts are made. Moreover, thecutting block can be made of polymeric material which may help reducethe cost of making the block. In addition, because polymeric material isrelatively lightweight compared to metal, the cutting block may berelatively lightweight which may improve the handling of the cuttingblock during a surgical procedure.

An aspect of the present application is a cutting block assemblycomprising interlocking first and second blocks for resecting a distalfemur. The first block has a first surface for providing a guidingsurface for making an anterior chamfer cut on the femur and a secondsurface for providing a guiding surface for making a posterior chamfercut on the femur. The second block is adapted to detachably couple tothe first block. The second block has a first surface for providing aguiding surface for making an anterior cut on the femur and a secondsurface for providing a guiding surface for making a posterior cut onthe femur.

Another aspect of the present application is a method of resecting adistal femur. The method includes attaching a first block to the distalfemur, the first block having a first surface providing a guidingsurface for making an anterior chamfer cut on the femur, a secondsurface providing a guiding surface for making a posterior chamfer cuton the femur, and making anterior and posterior chamfer cuts on thedistal femur. The method further includes attaching a second block tothe first block, the second block having a first surface providing aguiding surface for making an anterior cut on the femur, and a secondsurface providing a guiding surface for making a posterior cut on thefemur, and making anterior and posterior cuts on the distal femur.

Yet another aspect of the present application is a method of resecting adistal femur. The method includes attaching a first block to the distalfemur, the first block having a first surface providing a guidingsurface for making an anterior chamfer cut on the femur, a secondsurface providing a guiding surface for making a posterior chamfer cuton the femur. The method further includes attaching a second block tothe first block, the second block having a first surface providing aguiding surface for making an anterior cut on the femur, and a secondsurface providing a guiding surface for making a posterior cut on thefemur. The method further includes making anterior and posterior cuts onthe distal femur, detaching the second block from the first block, andmaking anterior and posterior chamfer cuts on the distal femur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the bone cutting blocks in anun-assembled configuration, in accordance with an embodiment of thepresent application.

FIG. 2 is an isometric view of the cutting blocks of FIG. 1 from adifferent angle.

FIG. 3 is a detailed isometric view of a first block of the cuttingblock assembly of FIG. 1.

FIG. 4 is a detailed partial isometric view of a second block of thecutting block assembly of FIG. 1.

FIG. 5 is an isometric view of the cutting block assembly of FIG. 1, inan assembled configuration.

FIG. 6 is a detailed partial isometric view of the cutting blockassembly of FIG. 5.

FIG. 7 is a detailed cross-sectional view of the cutting block assemblyof FIG. 5 taken along lines A-A.

FIG. 8A is an isometric view and FIG. 8B is a medial view of a distalfemur after a distal cut has been made on the surface of the distalfemur.

FIG. 9A is an isometric view and FIG. 9B is a medial view showing thefirst block of the cutting block of FIGS. 1-7 being attached to thedistal femur of FIGS. 8A-8B.

FIG. 10A is an isometric view and FIG. 10B is a medial view showing thefirst block attached to the distal femur of FIGS. 9A-9B in preparationfor making anterior and posterior chamfer cuts on the surface of thedistal femur.

FIG. 11A is an isometric view and FIG. 11B is a medial view showing thedistal femur of FIGS. 10A-10B after the anterior and posterior chamfercuts have been made.

FIG. 12A is an isometric view and FIG. 12B is a medial view showing thedistal femur of FIGS. 11A-11B with the second block being attached tothe first block.

FIG. 13A is an isometric view and FIG. 13B is a medial view showing thefirst and second blocks being interlocked to form a cutting blockassembly for making anterior and posterior cuts on the surface of thedistal femur of FIGS. 12A-12B.

FIG. 14A is an isometric view and FIG. 14B is a medial view showing thedistal femur of FIGS. 13A-13B after the anterior and posterior cuts havebeen made on the surface of the distal femur.

FIG. 15 is a medial view showing the distal femur of FIGS. 14A-14B afterthe cutting block assembly has been removed.

FIG. 16 is an isometric view of the bone cutting blocks in anun-assembled configuration, in accordance with another embodiment of thepresent application.

FIG. 17 is a side view of the cutting blocks of FIG. 16.

FIG. 18 is an isometric view of the second block of the cutting blockassembly of FIG. 16.

FIG. 19 is an isometric view of the cutting blocks of FIG. 16 in anassembled configuration.

FIG. 20 is another view of the cutting block assembly of FIG. 19.

FIG. 21 is a medial view of the cutting block assembly of FIG. 16 beingattached to a distal femur.

FIG. 22 is a medial view showing the cutting block assembly attached tothe distal femur of FIG. 21 in preparation for making anterior andposterior cuts on the surface of the distal femur.

FIG. 23 is a medial view showing the distal femur of FIG. 22 after theanterior and posterior cuts have been made.

FIG. 24 is a medial view showing the distal femur of FIG. 23 with thesecond block of the cutting block assembly being removed.

FIG. 25 is a medial view showing the distal femur of FIG. 24 with thesecond block removed in preparation for making posterior and anteriorchamfer cuts on the surface of the distal femur.

FIG. 26 is a medial view showing the distal femur of FIG. 25 after theanterior and posterior chamfer cuts have been made on the surface of thedistal femur.

FIG. 27 is a medial view showing the distal femur of FIG. 26 after thefirst cutting block of the cutting block assembly has been removed andthe four cuts have been made.

DETAILED DESCRIPTION

Referring to FIGS. 1-7, shown is a cutting block assembly generallydenoted as 10 comprising a first block 12 capable of interlocking with asecond block 14 to form a four-in-two (4-in-2) cutting block forresecting a portion of a bone such as a distal femur. Referring to FIGS.1-2, the first block 12 is a generally triangular shaped block formingan anterior-chamfer cutting surface 16, a posterior-chamfer cuttingsurface 18, a contact surface 20 and side surfaces 22. Theanterior-chamfer cutting surface 16 provides a guiding surface formaking an anterior-chamfer cut on a femur (not shown). Theposterior-chamfer cutting surface 18 provides a guiding surface formaking a posterior-chamfer cut on the femur. The contact surface 20includes protrusions 26 adapted to fit into holes in the distal femur todetachably couple the first block 12 to the distal resected surface of adistal femur (not shown), as explained below in further detail. In oneembodiment, the protrusions 26 are shown as cylindrical posts but canhave other shapes such as square. In one embodiment, the first block 12also may include angled pin holes 28 extending outwardly from thecontact surface 20 to the side surfaces 22. The pin holes 28 are adaptedto receive pins (not shown) to more firmly secure the first block 12 tothe distal resected surface of the distal femur. The cutting surfaces16, 18 of the first block 12 form a generally V-shaped portion 13 forcoupling to the second block 14, as explained below.

The second block 14 is a generally trapezoidal shaped block withV-shaped portion 15 sized to receive the V-shaped portion 13 of thefirst block 12. The second block 14 forms an anterior cutting surface30, a posterior cutting surface 32, contact surfaces 34, 36 and sidesurfaces 38. The anterior cutting surface 30 provides a guiding surfacefor making an anterior cut on the femur. The posterior cutting surface32 provides a guiding surface for making a posterior cut on the femur.The contact surfaces 34, 36 of the second block 14 form the generallyV-shaped open-faced portion or channel 15 which is complementary to thegenerally V-shaped portion 13 formed by the surfaces 16, 18 of the firstblock 12. In this manner, as explained above, the portion 13 of thefirst block 12 is capable of fitting within the portion 15 of the secondblock 14.

One possible feature of the cutting block assembly 10 is an interlockingmechanism for detachably securing the blocks 12, 14 to each other. In apreferred embodiment, the interlocking feature is a slidable couplingmechanism comprising holes 24 of the first block 12 adapted to receiveprotrusions 44 of the second block 14. Two protrusions 44 extendoutwardly from the surface 34 of the second block 14 and one protrusion44 extends outwardly from the surface 36. In a complementary manner, twoholes 24 extend through the surface 16 of the first block 12 and onehole 24 extends through the surface 18 of the first block. Theprotrusions are adapted to slide into and fit within the holes 24 toform an interlocking feature to detachably couple or interlock the firstblock 12 to the second block 14. Such an arrangement may provide variousadvantages. For example, as explained above, the first block 12 providesfor anterior and posterior chamfer cuts and the second block 14 providesfor anterior and posterior cuts. By using the interlocking feature tointerlock the first block 12 with the second block 14, the cutting blockassembly 10 allows the four distal femur cuts (anterior-chamfer,posterior-chamfer, anterior, posterior) to be tightly correlated to eachother which may help increase the accuracy of the cuts.

Another possible feature of the cutting block assembly 10 is that itprovides a mechanism to verify the accuracy of the posterior andanterior chamfer cuts before the anterior and posterior cuts are made.For example, in one embodiment, the second block 14 includes extendedportions 30 a, 32 a which extend beyond the contact surface 20 andcutting surfaces 16, 18 of the first block 12, as best shown in FIG. 7.The extended portions 30 a, 32 a include extended portions of contactsurfaces 34, 36, respectively, and extended portions of cutting surfaces30, 32, respectively. As explained below in detail, because the extendedcutting surfaces 30, 32, which are part of extended portions 30 a, 32 a,provide increased cutting surface area for making the anterior andposterior cuts which may help improve the accuracy of the anterior andposterior cuts. In addition, the contact surfaces 34, 36, which are partof portions 30 a, 32 a, extend onto the chamfer cuts which may allow auser to verify the anterior and posterior chamfer cuts made with thefirst block before making the anterior and posteriors cuts with thesecond block.

Another possible feature of the cutting block assembly is that it can bemade of relatively lightweight material which may provide variousadvantages. In one embodiment, the blocks 12, 14 are made of a polymericmaterial such as plastic which may help reduce the complexity and costof manufacturing the block. Moreover, because the blocks are made of apolymeric material, the blocks can be discarded after being used insteadof having to sterilize the blocks for subsequent use. However, theblocks 12, 14 can be made of other materials, such as metal, or othermaterials well known to one skilled in the art. In a preferredembodiment, the cutting surfaces 16, 18, 30, 32 are generally planar andsmooth. In another embodiment, the surfaces 16, 18, 30, 32 can benon-smooth with grooves or ridges on the surfaces. In a preferredembodiment, the contact surfaces 34, 36 of the second block 14 areformed with ribs 42 extending into the interior of the block which mayhelp reduce the amount of material and thus improve manufacturabilityand reduce the cost of manufacture. In addition, the use of lessmaterial and/or polymeric material may help make the cutting block morelightweight which may make the cutting block easier to use or manipulateduring a surgical procedure.

Another possible feature of the cutting block assembly is that itprovides a “keyed” mechanism to help ensure that the blocks areinterlocked in a proper manner. In one embodiment, the number andarrangement of the protrusions 44 and holes 24 provide a lockingmechanism which requires the blocks 12, 14 to be oriented and coupled toeach other in only a single configuration. The first block 12 includestwo holes 24 disposed over a single hole 24. In a complementary manner,the second block 14 includes two protrusions 44 disposed over a singleprotrusion. In this manner, the blocks 12, 14 can be coupled to eachother in only one orientation. That is, the anterior surfaces 16, 30 arerequired to be aligned to each other and the posterior surfaces 18, 32are required to be aligned to each other. This feature may help reducethe possibility of error during a surgical procedure. However, thenumber, size and arrangement of the protrusions 44 and holes 24 can beimplemented in other ways. For example, the arrangement can be reversed,with one protrusion disposed over the two protrusions and the holes 24configured in a similar manner.

Referring to FIGS. 3 and 4, shown are detailed views of the first block12 and second block 14 respectively of FIGS. 1-2. As explained above,the protrusions 44 of the second block 14 are adapted to fit within theholes 24 of the first block 12 to form an interlocking feature todetachably couple or interlock the blocks 12, 14 to each other. Theprotrusions 44 and the corresponding holes 24 are shown as generallysquare shaped but can have other shapes, such as cylindrical, as long asthey are complementary to provide a relatively secure interlock betweenthe blocks. The protrusions 44 have generally square shaped ramps 44 aon bottom surfaces of the protrusions. In a complementary manner, theholes 24 have generally square shaped ramps 24 a on bottom surfaces ofthe holes. The protrusions 44 are slightly yieldable to accommodate theramps 24 a of the holes, as explained below.

Referring to FIGS. 4, 5, 6, shown are detailed views of the first block12 and second block 14 of FIG. 1 in an assembled configuration. Toassemble the blocks 12, 14 to form assembly 10, the blocks 12, 14 areadvanced toward each other to permit the protrusions 44 of the secondblock 14 to be inserted into the holes 24 of the first block 12. Theblocks 12, 14 are further advanced toward each other such that theridges 44 a of the second block 14 contact the ramps 24 a of the firstblock 12. As the blocks 12, 14 are further advanced toward each other,the protrusions 44 yield upward and away from the ramps 24 a and theridges 44 a pass beyond the surface of the ramps 24 a and return totheir original position. Once the ridges 44 a are positioned behind thesurfaces of the ramps 24 a, the protrusions 44 are held in place in theholes 24 to provide a secure detachable coupling or interlock betweenthe blocks 12, 14. To detach the blocks 12, 14 from each other, theblocks are moved away from each other with sufficient force to cause theridges 44 a to slide over and away from the ramps 24 a thereby freeingthe blocks from each other.

Referring to FIGS. 8A-8B to 14A-14B, a description is provided of asurgical procedure for resecting a distal femur 52 of a femur bone 50using the cutting block assembly 10 of FIGS. 1-7 in accordance with anembodiment of the present application. Referring to FIGS. 8A-8B, thedistal femur 52 has an anterior portion 52 a, a medial portion 52 b, aposterior portion 52 c, and a lateral portion 52 d. In an initial stepof the surgical procedure, a distal cut is made which involves theresection or removal of a distal bone portion (not shown) from thedistal femur 52 leaving behind a generally flat resected distal surface56. A cutting device (not shown) can be used to remove the distal boneportion using conventional techniques. The cutting device can be a bonecutter such as an oscillating saw or other bone cutting devicewell-known to one skilled in the art. Once the distal cut has been made,pilot holes 54 can be drilled into the distal surface 56 in preciselocation and orientation as known to one skilled in the art toaccommodate the protrusions 26 of the first block 12 as shown in FIGS.9A-9B and described below.

FIG. 9A is an isometric view and FIG. 9B is a medial view showing thefirst block 12 of the cutting block assembly 10 of FIGS. 1-7 beingattached to the distal femur of FIGS. 8A-8B. The first block 12 isadvanced toward the distal femur 52 with the contact surface 20 of thefirst block 12 oriented to face the distal surface 56 of the distalfemur. The first block 12 is also oriented with the protrusions 26 ofthe first block being aligned with the holes 54 of the distal surface56. In addition, the first block 12 is oriented with the cutting surface16 (labeled “Anterior”) generally facing the anterior portion 52 a ofthe distal femur 52. The first block 12 is advanced toward the distalsurface 56 until the protrusions 26 enter the holes 54 of the distalsurface 56 and the contact surface 20 of the first block 12 is flushwith the distal surface 56, as shown in FIGS. 10A-10B and describedfurther below.

FIG. 10A is an isometric view and FIG. 10B is a medial view showing thefirst block 12 attached to the distal femur 52 of FIGS. 9A-9B inpreparation for making anterior and posterior chamfer cuts on thesurface of the distal femur 52. The first surface 16 of the first block12 provides a guiding surface for making an anterior-chamfer cut alongan anterior-chamfer plane 62. To make the anterior-chamfer cut, a bonecutting device such as a saw (not shown) is applied to the surface 16 ofthe first block 12 and advanced toward the distal surface 56 along theplane 62 until an anterior-chamfer bone portion 64 is removed. In asimilar manner, the second surface 18 of the first block 12 provides aguiding surface for making a posterior-chamfer cut along aposterior-chamfer plane 66. To make the posterior-chamfer cut, a cuttingdevice is applied to the surface 18 of the first block 12 and advancedtoward the distal surface 56 along plane 66 until a posterior-chamferbone portion 68 is removed. In one embodiment, holes (not shown) can bemade to the distal surface 56 through which pins (not shown) could beinserted through holes 28 of the first block 12 and into the holes ofthe surface 56. In another embodiment, self-drilling bone pins (notshown) can be used which don't require holes to be predrilled into thesurface 56. In both cases, the first block can be more firmly secured tothe distal surface 56 which may reduce the possibility of movement ofthe first block during the cutting process. As explained above, theanterior-chamfer cut is made and then the posterior-chamfer cut is made.However, the sequence of cuts could be reversed with theposterior-chamfer cut being made first and the anterior-chamfer cutbeing made second.

FIG. 11A is an isometric view and FIG. 11B is a medial view showing thedistal femur of FIGS. 10A-10B after the anterior and posterior chamfercuts have been made. Once the anterior-chamfer cut has been made, ananterior-chamfer surface 70 remains. Likewise, once theposterior-chamfer cut has been made, a posterior-chamfer surface 72remains. The distal femur 52 is now ready to have the second blockattached to the first block 12 and to have the anterior and posteriorcuts made as shown in FIGS. 12A-12B and explained below.

FIG. 12A is an isometric view and FIG. 12B is a medial view showing thedistal femur of FIGS. 11A-11B with the second block 14 being attached tothe first block 12. The second block 14 is advanced toward the firstblock 12 with the contact surface 34 of the second block facing thecutting surface 16 of the first block and the contact surface 36 of thesecond block 14 facing the cutting surface 18 of the first block. Thesecond block 14 is oriented with the protrusions 44 of the second blockbeing aligned with the holes 24 of the first block 12. The second block14 is then advanced toward the first block 12 until the protrusions 44of the second block 14 enter the holes 24 of the first block 12 and theblocks interlock, as shown in FIGS. 13A-13B and described further below.

FIG. 13A is an isometric view and FIG. 13B is a medial view showing thefirst block 12 and second block 14 being interlocked to form a cuttingblock assembly for making anterior and posterior cuts on the surface ofthe distal femur 52. As explained above, the cutting assembly 10 has aninterlocking feature which allows the blocks 12, 14 to be interlocked toeach other and to correlate the four distal femur cuts(anterior-chamfer, posterior-chamfer, anterior, posterior) to eachother. In this manner, the accuracy of the cuts may be increased. Theanterior cutting surface 30 of the second block 14 provides a guidingsurface for making an anterior cut along an anterior plane 74. In asimilar manner, the posterior cutting surface 32 of the second block 14provides a guiding surface for making a posterior cut along a posteriorplane 78.

As explained above, the cutting block assembly 10 has a cutting surfaceverification feature which provides the ability to verify the accuracyof the posterior and anterior chamfer cuts before the anterior andposterior cuts are made. Thus, before the anterior and posterior cutsare made, the second block 14 can be used to check or verify theaccuracy of the anterior and posterior chamfer cuts previously made bythe first block 12. For example, as explained above, the second block 14has extended portions 30 a, 32 a which extend beyond the contact surface20 and cutting surfaces 16, 18 of the first block 12 and onto thechamfer surfaces 70, 72. The extended portions 30 a, 32 a provide a userwith a visual indication of whether the chamfer surfaces have beenproperly cut. If any of the chamfer surfaces 70, 72 have been improperlycut, for example, having uneven or skewed surfaces, then a gap or spacewill be present between the chamfer surfaces and the extended portions30 a, 32 a indicating that cuts have been improperly made. In this case,a user can proceed to take remedial action such as reapplying the saw tothe chamfer surfaces to attempt to fix the imperfections.

However, if the chamfer surfaces 70, 72 have been properly cut, then nogap or space will be present between the chamfer surfaces and thecontact surfaces of the extended portions 30 a, 32 a indicating that thecuts have been properly made. In this case, a user can proceed to makethe anterior and posterior cuts using the second block 14. To make theanterior cut, a bone cutting device is applied to the surface 30 of thesecond block 14 and advanced toward anterior bone portion 76 and alongplane 74 until the anterior bone portion 76 is removed. To make theposterior cut, a cutting device such as a saw is applied to the surface32 of the second block 14 and advanced toward a posterior bone portion80 and along surface 78 until the posterior bone portion 80 is removed.In one embodiment, the anterior cut can be made first and the posteriorcut can be made second. However, in another embodiment, the posteriorcut can be made first and the anterior cut can be made second.

FIG. 14A is an isometric view and FIG. 14B is a medial view showing thedistal femur of FIGS. 13A-13B after the anterior and posterior cuts havebeen made on the surface of the distal femur. As explained above, theextended cutting surfaces 30, 32, which are part of extended portions 30a, 32 a, provide increased cutting surface area for making the anteriorand posterior cuts. As a result, the accuracy of the anterior andposterior cuts may be improved. Once the anterior cut has been made, ananterior surface 82 remains. Likewise, once the posterior cut has beenmade, a posterior surface 84 remains. At this point in the surgicalprocedure, the four cuts (anterior-chamfer, posterior-chamfer, anterior,posterior) have been made and the cutting block assembly 10 can beremoved as a single unit from the distal femur as shown in FIG. 15 andexplained further below.

FIG. 15 is a medial view showing the distal femur 52 after the four cutshave been made and the cutting assembly has been removed. The distalfemur 52 shows the four cuts (anterior-chamfer 70, posterior-chamfer 72,anterior 82, posterior 84) and the distal cut 56 made by the cuttingblock assembly of the present application. The distal femur 52 is nowready for further procedures including the implantation of a kneeprosthesis using conventional techniques.

Referring to FIGS. 16-20, shown is a cutting block assembly generallydenoted as 100 in accordance with another embodiment of the presentinvention. The cutting block assembly 100 comprises a first block 112capable of interlocking with a second block 114 to form a four-in-two(4-in-2) cutting block assembly for resecting a portion of a bone suchas a distal femur. The cutting block assembly 100 is similar to thecutting block 10 above. For example, referring to FIGS. 16-20, the firstblock 112 is a generally triangular shaped block forming ananterior-chamfer cutting surface 116, a posterior-chamfer cuttingsurface 118, a contact surface 120 and side surfaces 122. The contactsurface 120 includes protrusions 126 adapted to fit into holes in thedistal femur (not shown). The first block 112 also may include angledpin holes 128 extending outwardly from the contact surface 120 to theside surfaces 122. The second block 114 is a generally trapezoidalshaped block with V-shaped portion 115 sized to receive the V-shapedportion 113 of the first block 112. The second block 114 forms ananterior cutting surface 130, a posterior cutting surface 132, contactsurfaces 131, 133 and side surfaces 138. The cutting block assembly 100has many of the same features as the cutting block 10 above. Forexample, the cutting block assembly 100 provides an interlockingmechanism for detachably securing the blocks 112, 114 to each other.Also, the cutting block assembly 100 can be made of relativelylightweight material to provide many of the same advantages as inassembly 10.

However, unlike the second block 14 of the cutting block assembly 10 ofFIGS. 1-7 above, the second block 114 of the cutting block assembly 100of FIGS. 16-20 does not include extended portions 30 a, 32 a. Instead,the second block 114 includes an anterior contact surface 131 and aposterior contact surface 133. The anterior contact surface 131 isadapted to make contact with the anterior portion of the distal surfaceof the distal femur (not shown) and the posterior contact surface 133 isadapted to make contact with the posterior portion of the distal surfaceof the distal femur. In addition, the cutting block assembly 100 can beused for resecting a distal femur similar to the procedure describedabove in the context of cutting block assembly 10 of FIGS. 1-7, exceptthat the sequence of the cuts is reversed, as explained below in detail.That is, with the cutting block assembly 100, the anterior and posteriorcuts are made first and then the anterior and posterior chamfer cuts aremade second.

Referring to FIGS. 21-27, a description is provided of a surgicalprocedure for resecting a distal femur 152 of a femur bone 150 using thecutting block assembly 100 of FIGS. 16-20 in accordance with anotherembodiment of the present application. This procedure is similar to theprocedure explained with reference to FIGS. 9A-9B to 15A-15B in thecontext of cutting block assembly 10, except that the order of the cutsare reversed and the cutting block assembly 100 is attached to thedistal femur as a single unit, as explained below. Referring to FIG. 21,the distal femur 152 has an anterior portion 152 a and a posteriorportion 152 b. In an initial step of the surgical procedure, a distalcut is made which involves the resection or removal of a distal boneportion (not shown) from the distal femur 152 leaving behind a generallyflat resected distal surface 156. Once the distal cut has been made,pilot holes (not shown) can be drilled into the distal surface 156 inprecise location and orientation as known to one skilled in the art toaccommodate the protrusions 126 of the first block 112. In thisembodiment, the first block 112 is attached to the second block to formcutting block assembly 100. In this regard, the cutting block assembly100 is to be attached to the distal femur as a single unit. The contactsurface 120 of the first block 112 is oriented to face the distalsurface 156 of the distal femur. The first block 112 is also orientedwith the protrusions 126 of the first block being aligned with the holes(not shown) of the distal surface 156. In addition, the second block 114is oriented with the contact surface 131 facing the anterior portion ofthe distal surface 156 and the contact surface 133 facing the posteriorportion of the distal surface. The cutting block assembly 100 isadvanced as a single unit toward the distal surface 156, in thedirection shown by arrow 188, until the protrusions 126 enter the holes(not shown) of the distal surface 156 and the contact surface 120 of thefirst block 112 and the contact surfaces 131, 133 are flush with thedistal surface 156, as shown in FIG. 22 and described further below.

FIG. 22 shows the cutting block assembly 100 attached to the distalfemur 152 of FIG. 21 in preparation for making anterior and posteriorcuts on the surface of the distal femur 152. In one embodiment, pins 129could be inserted through holes of the first block 112 and into theholes of the distal surface 156 to more firmly secure the assembly 100to the distal surface 156. The first surface 130 of the second block 114provides a guiding surface for making an anterior cut along an anteriorplane 174. To make the anterior cut, a bone cutting device (not shown)is applied to the surface 130 of the second block 114 and advancedtoward the distal surface 156 along the plane 174 until an anterior boneportion 176 is removed. In a similar manner, the second surface 132 ofthe second block 114 provides a guiding surface for making a posteriorcut along a posterior plane 178. To make the posterior cut, a cuttingdevice (not shown) is applied to the surface 132 of the second block 114and advanced toward the distal surface 156 along plane 178 until aposterior bone portion 180 is removed. In another embodiment, thesequence of cuts could be reversed with the posterior cut being madefirst and the anterior cut being made second.

FIG. 23 shows the distal femur of FIG. 22 after the anterior andposterior cuts have been made. Once the anterior cut has been made, ananterior surface 182 remains. Likewise, once the posterior cut has beenmade, a posterior surface 184 remains. The second block 114 can now bedetached from the first block 112 in preparation for making the anteriorand posterior chamfer cuts as shown in FIG. 24 and explained below.

FIG. 24 shows the distal femur of FIG. 23 with the second block 114being detached from the first block 112. The second block 114 is movedaway from the first block 112, in the direction shown by arrow 190, withsufficient force to detach the second block from the first block butwith the first block remaining attached to the distal femur. Once thesecond block 114 has been removed, the distal femur 152 is ready to havethe anterior and posterior chamfer cuts made as shown in FIG. 25 andexplained below.

FIG. 25 shows the first block 112 attached to the distal femur 152 readyfor making anterior and posterior chamfer cuts on the surface of thedistal femur 152. The anterior cutting surface 116 of the first block112 provides a guiding surface for making an anterior-chamfer cut alongan anterior plane 162. In a similar manner, the posterior cuttingsurface 118 of the first block 114 provides a guiding surface for makinga posterior-chamfer cut along a posterior plane 166. To make theanterior-chamfer cut, a bone cutting device is applied to the surface116 of the first block 112 and advanced toward anterior bone portion 164and along plane 162 until the anterior bone portion 164 is removed. Tomake the posterior-chamfer cut, a cutting device is applied to thesurface 118 of the first block 112 and advanced toward aposterior-chamfer bone portion 168 and along surface 166 until theposterior-chamfer bone portion 168 is removed. In another embodiment,the posterior-chamfer cut can be made first and the anterior-chamfer cutcan be made second.

FIG. 26 shows the distal femur of FIG. 25 after the anterior andposterior chamfer cuts have been made on the surface of the distalfemur. Once the anterior-chamfer cut has been made, an anterior-chamfersurface 170 remains. Likewise, once the posterior-chamfer cut have beenmade, a posterior-chamfer surface 172 remains. At this point in thesurgical procedure, the four cuts (anterior-chamfer, posterior-chamfer,anterior, posterior) have been made and the first block 112 can bedetached from the distal femur by removing the pins 129 from the firstcutting block and distal femur and moving the first block 112 away fromthe distal femur in the direction shown by arrow 192.

FIG. 27 shows the distal femur 152 of FIG. 26 after the four cuts havebeen made and the cutting assembly has been removed. The distal femur152 shows the distal cut 156 and the four cuts (anterior-chamfer 170,posterior-chamfer 172, anterior 182, posterior 184) made by the cuttingblock assembly 100 of the present application. The distal femur 152 isnow ready for further procedures including the implantation of a kneeprosthesis using conventional techniques.

The cutting block devices of the present application may provide variousadvantages. The cutting block device is a four-in-two (4-in-2) cuttingblock assembly which may improve accuracy in the preparation of thedistal femur for the implantation of a knee prosthesis. The cuttingblock assembly comprises a first block for making the anterior andposterior chamfer cuts and a second block for making the anterior andposterior cuts. The first and second blocks interlock which may helpimprove the correlation between the four cuts and improve the accuracyof the cuts. In one embodiment, the second block includes extendedsurfaces which may help improve the accuracy of the anterior andposterior cuts. In addition the extended surfaces of the second blockmay help provide a visual indication of the accuracy of the chamfer cutsbefore the anterior and posterior cuts are made. Moreover, the cuttingblock can be made of polymeric material which may help reduce the costof manufacture and may improve the handling of the cutting block duringa surgical procedure.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A method of resecting a distal femur, the method comprising:attaching a first block to the distal femur, the first block having afirst surface providing a guiding surface for making an anterior chamfercut on the femur, and a second surface providing a guiding surface formaking a posterior chamfer cut on the femur; making anterior andposterior chamfer cuts on the distal femur; attaching a second block tothe first block, the second block having a first surface providing aguiding surface for making an anterior cut on the femur, and a secondsurface providing a guiding surface for making a posterior cut on thefemur; and making anterior and posterior cuts on the distal femur. 2.The method of claim 1, further comprising checking accuracy of theanterior chamfer cut before the making of the anterior or posteriorcuts.
 3. The method of claim 2, wherein the checking of the accuracy ofthe anterior chamfer cut includes checking for a gap or space between acontact surface on the second block and the resected bone surface,wherein the contact surface of the second block is parallel to the firstsurface of the first block.
 4. The method of claim 1, further comprisingchecking accuracy of the posterior chamfer cut before the making of theanterior or posterior cuts.
 5. The method of claim 4, wherein thechecking of the accuracy of the posterior chamfer cut includes checkingfor a gap or space between a contact surface on the second block and theresected bone surface, wherein the contact surface of the second blockis parallel to the second surface of the first block.
 6. A method ofresecting a distal femur, the method comprising: attaching a first blockto the distal femur, the first block having a first surface providing aguiding surface for making an anterior chamfer cut on the femur, and asecond surface providing a guiding surface for making a posteriorchamfer cut on the femur; attaching a second block to the first block,the second block having a first surface providing a guiding surface formaking an anterior cut on the femur, and a second surface providing aguiding surface for making a posterior cut on the femur; making anteriorand posterior cuts on the distal femur using the second block; detachingthe second block from the first block; and making anterior and posteriorchamfer cuts on the distal femur using the first block.
 7. The method ofclaim 6, further comprising detaching the first block from the distalfemur.
 8. The method of claim 6, further comprising inserting one ormore pins through the first block and into the distal femur to securethe first block to the distal femur.
 9. A method of resecting a distalfemur, the method comprising: attaching a cutting block assembly to thedistal femur, wherein the cutting block assembly comprises a first blockdetachably coupled to a second block, the first block having a firstsurface providing a guiding surface for making an anterior chamfer cuton the femur, and a second surface providing a guiding surface formaking a posterior chamfer cut on the femur, and the second block havinga first surface providing a guiding surface for making an anterior cuton the femur, and a second surface providing a guiding surface formaking a posterior cut on the femur; making anterior and posterior cutson the distal femur using the second block; detaching the second blockfrom the first block; and making anterior and posterior chamfer cuts onthe distal femur using the first block.
 10. The method of claim 9,further comprising detaching the first block from the distal femur. 11.The method of claim 9, further comprising inserting one or more pinsthrough the first block and into the distal femur to secure the firstblock to the distal femur.